/**
 * 替换字符串的某一位字符
 * @param {string} str
 * @param {string} index
 * @param {string} value
 * @return {string}
 */
export default function replaceStr(str, index, value) {
  const front = str.slice(0, index);
  const back = str.slice(index + 1, str.length);
  return front + value + back;
}
